Calculating machine



Dec. 1, 1936. H. T. AVERY CALCULATING MACHINE s Sheets-Sheet 1 Original Filed June 1, 1931 INVENTOR fi/aro/d 7: fit/e A TTORNE Y LZJWX Dec. 1, 1936. H. T. AVERY CALCULATING MACHINE 8 Sheets-Sheet 2 Original Filed June 1, 1931 m muHFmH INVENTOR fiar'o/a 7: /1 very BY ATTORNEY Dec; 1, 1936. H. T. AVERY I 2,062,634

CALCULATING MACHINE Original Filed June 1, 1931 8 Sheets-Sheet 3 FIE- E ATTORNEY 1936- H. 1". AVERY CALCULATING MACHINE Original Filed June 1, 1931 8 Sheets-Sheet 4 INVIENTOR Harv/a 72/] Very ATTORNEY Dec. 1, 1936. H. T. AVERY CALCULATING MACHINE Original Filed June 1, 1931 a Sheets-Sheet 5 INVENTOR Harp/d [five/ y ATTORNEY Dec. 1, 1936.

H. T. AVERY CALCULATING MACHINE Original Filed June 1, 1931 8 Sheets-Sheet 6 ml mu firmn I is: 1 N llll llilfrgg INVENTOR Harv/a TAVQ/y 2 nw ATTORNEY Dec; 1, 1936. H. T. AVERY CALCULATING MACHINE Original Filed June 1, 1931 8 Sheets-Sheet 7 m mHFmn mwow w /y VT m @n M2 0 W Dec. 1, 1936. H. T. AVERY CALCULATING MACHINE Original Filed June 1, 1931 8 SheetS She et 8 FLE, 1a.

INVENTOR Harv/d 7.7? very ;%W%

ATTORNEY Patented Dec. 1, 1936 PATENT OFFICE CALCULATING MACHINE Harold T. Avery, Oakland, Calif., assignor to Mar-chant Calculating Machine Company, a corporation of California Application June 1, 1931, Serial No. 541,286

' Renewed December 26, 1935 7 Claims. (01. 235-63) The present invention relates to calculating machines of the type adapted to perform the four primary calculations, and particularly to the type embodying means whereby division operations are performed automatically.

It is an objector the present invention to provide an improved mechanism for the automatic performance of problems in division.

Another object of the invention is to provide means whereby the automatic division control lever may be restored to inoperative position without affecting the completion of an operation.

A further object of the invention is to provide means whereby the machine will invariably be automatically stopped at the end of a corrective stroke of the actuator.

'A further object of the invention is to provide means whereby the automatic division control lever must be given a full stroke before it can be restored to inoperative position.

A further object of the invention is to provide means whereby the overdraft control mechanism may be optionally controlled from any one of a plurality of orders of the actuating mechanism.

Other objects will appear as this specification the apparatus has been shown, but it is to be understood that the invention has not been limited to'such form, since the invention, as set forth in the claims, may be embodied in a plurality of other forms.

It is manifest that the invention may be embodied in any calculating machine in which the registering mechanism and the differential controlling mechanism therefore are relatively displaceable with respect to each other; however, in the accompanying drawings, it is shown embodied in a machine of the general type disclosed in the patent to Friden No. 1,643,710 dated September 27th, 1927, to which reference is hereby made for a disclosure of such mechanisms as are not specifically described herein. I

In the accompanying drawings, forming a part of this specification: v

Figure 1 is a longitudinal section looking toward he right showing the drive and power control nechanism. 1 a

Figure 2 is a longitudinal section showing the plus and minus bar structures.

Figure 3 is a rear elevation of the machine showing the reversing gear and division control mechanisms with certain parts thereof in section.

Figure 4 is a detail of a portion of the division control mechanism.

Figure 4A is a section taken along the line lA-AA in Figure 3 and shows in detail the means for preventing shifting of the reversing means while the actuator is out of'full-cycle position.

Figure 5 is a longitudinal section showing the division control lever and associated mechanism.

Figure 6 is a longitudinal section showing the automatic division release key and a portion of the control mechanism.

Figure 7 is a longitudinal section showing the automatic division mechanism and its control of the actuator selection lock.

Figure 8 is a longitudinal section through a portion of a machine showing the overdraft control mechanism. 7

Figure 9 is a plan view of the overdraft control restore cam.

Figure 10 is a plan view of a single actuator element, and the associated tens transfer mechanism.

Figure 11 is a plan view of the overdraft control mechanism.

Figure 12 is a fragmentary rear elevation of the machine showing in section one form of arrangement to effect optional control of theoverdra-ft mechanism.

Figure 13 is a section taken along the line l3l3 of Figure 12 showing the overdraft op-- tional control lever.

Actuator, accumulator, and counter 'sion thereof, introduce into said actuator values corresponding to the numerals delineated thereon, the rotation of said actuator serving to transfer these values to the numeral wheels of the acdenominational order.

Each of these registering mechanisms is pro vided with suitable tens transfer means, a disclosure of which may be found in the above mentioned patent, and other associated mechanisms which will be described in full as this specification progresses.

Drive control In the present embodiment, the driving mechanism comprises an electric motor which is connected to the drive shaft I 00 by appropriate speed reducing gearing and is adapted to be intermittently connected to the calculating mechanism to drive the same.

The means whereby the drive is connected to the calculating mechanism includes a clutch IIO (Figure 1), the driving member of which is a toothed wheel III, fixed on one end of the drive 'shaft I00. Enclosing the toothed wheel III is a circular housing I I2 which constitutes the driven member of the clutch, and pivoted within this housing in a position to engage the toothed wheel III, is a driving pawl II3. This pawl is normally pressed into engagement with the toothed wheel by means of the inset compression spring II4, but is adapted to be maintained in its nonengaging position by means of the clutch control mechanism. The clutch control mechanism comprises a bellcrank member II5 journaled on a stub-shaft IIS on the machine frame and carrying on one arm a foot III adapted, when the actuator is in full cycle position, to project through an appropriately positioned aperture in the clutch housing II2 to engage the tail of the pawl H3 and urge it to clutch disengaging position.

A spring II8, tensioned between a stub on the machine base and the opposite arm of the bell crank II5 tends to urge the foot III into clutch disengaging position, so that in the absence of intervention by other instrumentalities the actuator will be brought to rest with the clutch in disengaged position when it reaches full cycle position after a rotation. Means are provided for operating the bell crank II5 to engage the actuator for the number of rotations requisite to perform a desired calculation, and pin 3 is provided on the forward end of the bell crank for this purpose.

Pin H9 is engaged by the notched rear end of the control link I2I which is pivoted at its forward end to control plate I20 and normally held in position overlying the pin H0 by spring I22 tensioned between the shaft I23 and an intermediate point on the control link. Control plate I20 is fixed to shaft I23 journaled in the machine, and comprises a forward vertical portion I24 adapted to cooperate with the plus bar and a rearward inclined portion I25, adapted to cooperate with the minus bar. Operation of either of these bars is adapted to impart a counterclockwise oscillation to control plate I20, as will be hereinafter described. This imparts corresponding counter-clockwise oscillation to the clutch operating bell crank H5 permitting engagement of the driving pawl ill for the period that such adjustment is maintained. The means whereby the plus and minus bars accomplish this end will be described hereinafter.

Reversing gearing ing, are two gears I3I and I32. On their contiguous faces these gears are provided with annular flanges I33, each of which is provided with two oppositely disposed seats of different depth, designed to receive pin I34 fixed in shifting shaft I35, and adapted to engage said seats through oppositely disposed orifices in the sleeve I30. A shifting of the pin I34, then, by means of the shaft I35, causes one or the other of the two gears to be engaged for drive by the clutch housing.

One of these gears includes an intermediate idler I3IA in its driving train to the actuator, which the other omits, and they therefore serve to drive the actuator in opposite directions, as shown in the side view Figure 6. This portion of the mechanism is fully disclosed in the patent to Friden, Number 1,682,901, of September 4th, 1928. In Figure 3, the pin I34 is shown so positioned as to drive the actuator in the additive direction, into which position it is normally urged by the spring 226 (Figure 2) supporting the minus bar.

Means are provided for shifting the shaft I35 (Fig. 3) to carry the pin into engagement with the negative driving gear I32. This means is made resilient so that its control may be superseded by other controls operative in automatic division operations, as will be hereinafter set forth. The shaft I35 carries a fixed collar I40 which is enclosed by a slidable sleeve Hi.

This sleeve also encloses a compression spring I42, one end of which bears against the collar, and the other end of which bears against one end of the sleeve, thus maintaining the sleeve in such a position over the collar that its other end bears against the collar. The shifting fork shown in Friden Patent No. 1,643,710 engages this collar I as shown at I43, and lateral motion thereof tends to shift the shaft I35 and its pin I34 into engagement with either of the two driving gears selectively.

Manual reversing means have also been provided whereby the accumulator actuator and counter actuator can be set to rotate either in the same direction or opposite directions from each other. This is accomplished by movement of a lever I50 (Figure 3) which, through a worm cam provided on its lower extremity, slides the shaft I5I laterally which, in turn, through a fork I52, positions the gear I53 to operate either direct or through an idler gear. This mechanism is fully disclosed in the patent to Friden No. 1,643,- 710, and the necessity for it is obvious when it is understood that the counter register must count subtractive rotations of the machine, by showing increasing values, during division and subtraction, and must also show increasing values while counting additive rotations of the machine during addition and multiplication operations.

Plus and minus bars Selectively operable manual means are provided for controlling the engagement and direction of the drive. The means for manually controlling rotation in the forward direction comprises a plus bar 200 (Figures 1 and 2) supported on a frame 20I. This frame is supported on one end of a pair of parallel links 202 which are connected together at their opposite ends by a link 203 and are pivoted intermediate their ends to the plate 2I0. Tension spring 204 tends to hold the plus bar in its elevated position. The frame 20I carries a roller 205 which extends through an aperture in the plate H0 and abuts the forward vertical end I24 of control plate I20 (Figure 1). Due to the manner in which the frame is mounted iipon'the parallel links, depression of the plus bar causes the roller to be moved downwardly and to the rear, rocking the control plate in a counterclockwise direction to effect engagement of the main clutch in the manner hereinbefore set forth.

The manual means for controlling reverse engagement of the drive comprises a minus bar 220 slidably mounted on the intermediate plate 2I0 by means of a pin and'slot connection. The stem of this key carries a roller 225 abutting the rearward inclined portion I25 of the control plate I20 and adapted on depression of the key to rock the plate in a counter-clockwise direction, effecting engagement of the main clutch. Pivoted on the opposite side of the intermediate plate 2I0 (Fig ure 2) is a bell crank 223. The lower arm of this bell crank is connected by link 221 with the worm cam 228 (Figure 6) which controls the reversing gear, while the upper arm of the bell crank underlies a pin 222 on the stem of the minus bar. De-

pression of this key, therefore, in addition to effecting engagement of the drive, operates the reversing gear to reverse the direction of the drive. To prevent concurrent depression of the plus and and minus bars an interlock is provided comprising a bar 230 pivoted on the intermediate plate v between the two keys and having one arm underlying the roller 205 of the plus bar, while its other end underlies the upper arm of hell crank 223. Depression of either key rocks the bar to prevent suificient depression of the other key to effect machine operation.

Automatic division Automatic division in each denominational order is performed in the present machine upon entry of the factors in the usual manner, setting the reversin'g lever to cause additive rotations of the counter register, setting the carriage, and shifting the division control lever 600 tov its forward position, which causes rotation of the actuator in the subtractive direction a suificient number of times to subtract the selected decimal multipleof the divisor from the dividend, registering said number of subtractions in the counter, in the usual manner, until an overdraft occurs. The occurrence of 'an overdraft operates controls which effect a reversal of the actuator driving gear without effecting a" disengagement of the actuator driving clutch.- The additive cycle immediately following the overdraft cycle therefore corrects the overdraft and a control operative in this cycle restores the reversing mechanism to its normal subtractive direction which will cause other overdraft and corrective cycles unless the operator has permitted the division control lever to resume its rearward neutrallpo'sition. These rocking cycles' less of the direction in which the actuator may be rotating at the time the division control lever 600 is released, the actuator will always be stopped at the end of a corrective rotation.

The automatic division lever 600 (Figure 5) is pivoted at GM to a side frame of the machine, and its upper end is rocked toward the front of the machine to initiate a division operation. This motion causes the lower extremity of the lever to impart a rearward displacement to the division slide IiI0 on its supporting stud 62I, against the force of the spring 602 suitably tensioned between a stud in the base of the machine and an intermediate point on the slide. The connection between the slide H0 and the division lever 600 is effected through a long slot and pin arrangement 604so that the slide will be displaced to the rear by the lever 600, but will not be returned with the lever to inoperative position. Spring 622 may therefore return the division lever 600 to inoperative position as soon as it is released by the operator leaving the division slide IiI0 latched in operative position by the mechanism hereafter described. v

A latching pawl 605 is pivoted on the side frame of the machine at 606, the head of which oooperates with a notch 601 in an intermediate portion of the division slide 6I0, into which it is pressed by the spring 608 compressed between a portion of the pawl and a suitable projection from the side frame. By these means, the division slide 6I0 is latched in the rearward position to which it is forced by an operation of the division lever 600 until the latch pawl 605 is raised by instrumentalitles which will be described hereinafter.

Suitably spaced from its rear end, the division slide 6I0 carries a laterally extending projection 609, the remote end of which lies directly in front of a vertical portion of the minus bar reversing link 221A (Figure 2) so that rearward motion of the slide BIO will serve to move the link 221 and place the gear control in position to cause subtractive rotation of the actuator.

Means have been provided whereby the main clutch is' released upon a forward stroke of the division lever 600. An intermediate portion of the projection 609 on division slide IiIIl lies directly in front of a substantially vertical portion of the bar BII (Figure 7) supported on the parallel links 6I2 and H3 and normally held in its forward position by means provided therefor, so

that a rearward movement of projection 609 will impart a rearward and downward movement to the bar GI I. This movement of bar 6 imparts a counter-clockwise rotation to shaft I23 by means of a roller 6I5 journaled on a stud in the bar 6| I, contiguous to and in front of a lever GIG secured to theshaft I23. Themanner in which a counter-clockwise rotation of the shaft I23, secured to the control plate I20 (Figure 1) effects a releasing of the main clutch IIO has been described heretofore. Obviously, then, the clutch releasing mechanism is locked'in released position by latch 605 (Figure 5), and the actuator is rotated continuously, subtracting the divisor or its decimal multiple from the dividend set in the accumulator carriage at each successive rotation until an overdraft occurs. The latch is automatically raised at the end of each corrective cycle if the operator has previously released the division lever 600 so that it may resume its inoperative position. In'an overdraft operation, as is well known in the art, a borrowing carry operation occurs which results in all efi'ective numeral wheels to the left of those actuated being operated from their normal zero registration to a nine registration.

The movement of the'faniili'ar carrying mechanism of the machine in this operation is utilized to control the reversal of the actuator to effect a correction of the overdraft. The carry mechanism includes carrying levers. 425 (Figure 8) normally latched in their forward position as shown, but adapted to be tripped to their rearward position by lug 426 on the numeral wheel in a direct transit from zero to 9, where tl-,-y are resiliently latched until restored after the operation. Di-

rectly behind the carry lever 425 of the numeral wheels cooperating with the next to the last carrying order of the actuator toward the left, is a lever 630 (Figure 11), which is splined on a shaft 615 and which is normally held against the lever 425 by spring 630A. The lever 630 is held against transverse movement by the bracket 680 and movement thereof in a vertical plane and a rocking of the shaft 615 ensues when a carry lever 425 is tripped. Pivoted for movement in a horizontal plane to the end of the lever 630 at 632, is a bifurcated tailpiece 633, which is normally held in its inoperative position by a vertical arm 650 of the slide bar 65I disposed between the bifurcated ends of said tailpiece in such a manner that transverse displacement of the arm in either direction results in a like displacement of the tailpiece about its pivot point 632. The division slide Bill is provided on its under side with a projection 6I'I (Figures 4 and 8) contiguous with a cam surface 652 on the end of the transverse slide 65I so that a rearward movement of the division slide 6I0 will result in a transverse movement of the slide 65I (Figures i 3 and 4) to the right against the tension of spring 654, said slide being mounted on the base of the machine by pin and slot connections 653.

Transverse movement of slide 65I and arm 650 to the right causes movement of the tailpiece 633 of the lever 630 into operative position overlying a horizontal arm 655 of a lower extremity of the bellcrank 656 pivoted at 651 on a second lever 659 (Figures 3 and 8) which is pivoted to the frame of the machine at 63I. Pivoted to the lever 659 at 660 is a depending link 66I, the lower end of which engages one arm of a bellcrank 662 pivoted to a standard 663 on the machine base. A spring 66IA is suitably tensioned between the lower arm of bellcrank 662 and a stud on link 66I to maintain said arm and said link in engagement. The vertical arm 662A of the bellcrank 662 operates against a collar 664, on the shaft I35, in such a manner that rocking of this bellcrank through downward pressure on link 66I shifts the shaft I so that it carries its pin I 34 into engagement with the gear I3I which serves to drive the actuator in the additive direction. This shift is positively brought about by means driven from the actuator and controlled by the numeral wheels in an overdraft operation.

In this operation, it is necessary to time the movement of lever 630 so that it is effected somewhat before the actuator reaches full cycle position, at which point the reversal takes place. For this purpose, the front end of lever 630 is constructed in the form of an L (see Figure 11), the wing of which lies behind the three levers 425 cooperating with the last three orders of the actuator, so that the third transfer pin from the left trips the overdraft control mechanism, this pin being farther from full cycle position than the last on account of the spiralling of these pins around the periphery of the actuator drum.

The overdraft control is exerted by the lowest.

order transfer lever 425 which is aligned with the wing of lever 630, the movement of lever 630 depressing its tailpiece 633 which, in turn, depresses the horizontal portion 655 (Figures 3 and 11) of lever 656 against the compression of lpring 658. The upper arm of lever 656 is adapted to position a pin 645 slidably mounted in a socket in the uppper end of lever 659 and arranged to be retained in either of its two adjusted positions by a spring pressed ball indicated at 646 (Figure 3). These operations occur just before the actuator reaches its full cycle position and their result is to project the end of the pin 645 into a position where it will be engaged by a specially formed cam face 634 on a plate 635 fixed on the right end of the actuator shaft as viewed in Figure 3. This engagement, taking place while the actuator is still being driven in the subtractive direction, drives the system including lever 653, link 66I, bellcrank 662 and shaft I35 to positively carry the pin I34 out of its seat in gear I32 and into its seat in gear I3I just as the actuator reaches full cycle position, and against the compression of spring I42 which is compressed in this operation, rendering unnecessary a release of the link 221 (Figure 2) which normally controls the positioning of pin I34 and also controls the main actuator clutch. Thus, it will be understood that the actuator is reversed without disengaging the main clutch, and enters upon an additive or corrective cycle.

Pressure on the linkage system above outlined is immediately relieved upon reversal of the actuator, but a reseating of the pin I34 in the gear I32 under pressure of spring I42 is prevented by the displacement of the seat therein from alignment with the seat in gear I3I. Reseating of the pin I34 in the gear I32 at half cycle position when the seats in gears I3I and I32 are again aligned is prevented by means of a disk I60 (Figures 3 and 4A) secured to the shaft I35, said disk being provided with a notch I 60A which when the actuator is in full cycle position is aligned with a lug I62A depending from a shaft IN. The arrangement is such that the disk I50 is positioned either to the right or the left of the lug I62A on adjustment of the pin I34 and prevents subsequent readjustment thereof until the actuator is again in full cycle position. Toward the end of the single cycle of additive or corrective rotation, the pin 645 is restored to its inoperative position by the cam face 63! (Figures 8 and 9) and at the end of the cycle the notch IIiIIA being aligned with the lug IBZA, the spring I42 becomes effective to shift the pin I34 into engagement with the gear I32 and another subtractive cycle of operation is initiated and consequently, another overdraft will occur.

This sequence of successive reversals of the actuator will continue until the operator has released the division lever 600 (Figure 5) permitting it to resume its rearward or inoperative position, to effect disengagement of the main clutch and a subsequent arresting of the actuator at the termination of the first additive rotation thereafter. Secured to the shaft 400 that carries the counting register transfer drum is a disk 638 (Figure 5) which, when the machine is set to perform problems in division, rotates in a clockwise direction while the actuator is rotating sub-' tractively, and rotates in a counter-clockwise direction while the actuator is rotating additively. A pin 639, projecting laterally from the disk 636, serves to operate mechanism during the corrective rotation of the actuator that results in stopping the machine.

The means for stopping the machine comprises a slide 640 which is free to slide on and pivot on the stud 6, and normally urged upward and around clockwise toward stop pin 643 by 76 lems in division, lies in'the path of pin 639. The

slide 646, however, is normally held so that the foot 644 is out of the path of thepin 639, there fore rendering, the slide 646 non-functional except during problems in division. With the division mechanism inoperative, thelower end of the slide 646 is in contact with and resting on shelf 6I6A formed on the end of the division slide 6I6 which is then in its forward position, resulting in the foot 644 being rocked about its pivot sufficiently to render it inoperative.

When the division lever 666 is pulled to its forward or operating position, then, the division slide 6|6 will be displaced to and latched in its rearward position, permitting the slide 646 to be rocked against its stop pin 643, thereby placing the foot 644 in, the path of the pin 6,39. Upon clockwise rotation of the disk 638, the pin strikes the beveled surface of the foot 644, causing the slide 646 to be angularly oscillated about its pivot 6 which performs no function. As a consequence of an overdraft registration, the direc-- tion of rotation of the disk 6361s reversed, causing the pin 639 to strike the flat end of the foot 644 and thus move the slide 646. downward and forward which movement is also ineffective unless the operator has pushed the division lever 666 to its rearward inoperative'position.

As hereinbefore explained, the retraction of division lever 666 to its rearward position does not release division slide 6l6 from its latching member 665, but merely positions other instrumentalities which will effect this release at the end of a corrective rotation of the actuator. The rearward angular displacement of the division lever 666 about its axis 66l serves to impart a rearward oscillation to a release bar 646, journaled on its forward end at 666A on the upper I arm of the lever 666, and slidabiy supported at itsrear end on pin 665A secured to the rear extremity of latch 665. In its rearward position the rear end of the release bar 645 lies in the path of a lateral projection 646A of the slide 646, so that a downward movement of the slide 646, caused by its foot 644 being forced down by pin 639 during a corrective or counter-clockwise cycle of the disk 636, will impart a like downward movement to release bar 645 about its pivot 666A, thereby imparting a counter-clockwise rotation of the latch 665 about its pivot 666 through a sumcient arc to lift its forward end out of the notch 66'! in division slide 6l6. This obviously releases the slide 6I6permitting the spring 662 to pull it to its forward inoperative position, and, in so doing, the machine is automatically stopped and the reverse mechanism is restored to effect its normal additive direction of the actuator, through meansof the pin 669, the functions of which have been described heretofore.

Means are provided wherebythe division slide 6|6 may be manually released in the event that mediate point on the slide and a stud suitably located in the machine. A camming surface 6463 provided on the forward end of the slide 648 is disposed directly underneath a similar camming surface 665A on the automatic division release key 666 which is also slidably supported in the machine and normally held in its elevated position by the spring 666. The camming surfaces 665A and 6463 are so positioned that depression of the release key 665 will move the slide 648 backward, which, through its pin 646A serves to impart a clockwise oscillation to the bellcrank 646 (Figure 5), consequently raising the latch 665 out ofthe notch 661, thereby permitting the division slide M6 to spring forward, resulting in stopping the machine. This manual stopping means is used to stop the machine only when it is observed that the human element has caused the introduction of an error. I

When the division lever. 666 has been pulled over halfway to its forward or operating position, means have been provided whereby it cannot be returned until a full forward stroke has been completed. During the forward stroke of lever 666 while it is being pulled to its operative position to initiate the operation of division, it is obvious that all contacts must necessarily have been made and the machine must have been started just before the latch 665 drops into the notch 661 on the slide NO. If, in this unlatched position, it were possible for the operator to restore the lever 666 to its rearward position before the correct number of subtractions had been made to cause an overdraft or complete the division operation in a particular denominational order, an

erroneous result would be obtained, while a. full stroke of the lever 666 before it is returned, will always result in the completion of the correct number of subtractions before the machine is stopped by a corrective cycle following an overdraft.

This full stroke mechanism comprises slide 626 (Figure 5) which is fulcrumed at 663 on the lower extremity ofthe division controllever 666 and is slidably supported at its rear end on the stud 62 I, said slide and said lower extremity being held in their normal forward position bya spring 622 tensioned between this slide and a stud in the machine base. A plurality of ratchet teeth 626B areprovided on the top edge of the slide 626 toward its rear end and intermediate two depressions 626A and 626C formed therein. Normally disposed in the rear depression 626A where it is held by tension of spring 624 is a nose 626A of the ratchet lever 623 pivoted on stud 666. Since the ratchet teeth 6263 are higher than the lower end of the nose 623A, it is obvious that, during a rearward displacement of the slide 626, the teeth 6263 will cause an angular displacement of the nose 623A sunlciently past its fulcrum point 666 to prevent the return of the slide 626 until all of the ratchet teeth 6263 have been engaged and Power control and interlocks Means are provided for controlling the circuit of the driving motor to effect closure thereof only when one of the several machine controls is functioning. Two normally open spring blade contacts 888 (Figure l) are connected in series in the motor circuit and are mounted in a suitable insulating block fixed' to the shaft 88l, journaled in the frame. Clockwise oscillation of shaft 88! is adapted to bring the near contact blade against abutment 882, to effect a closure of the contact. One means for producing this oscillation of the shaft comprises a lever 883, fixed to one end thereof, and, connected by a push link 884, a shouldered end of which is retained in a slot in lever 883, and rod 885, to a lever 888 fixed to shaft 881 journaled in the frame. The lever 888 lies directly behind and in contact with clutch control bellcrank H5, so that a rocking of this bellcrank to cause engagement of the actuator clutch will rock lever 888 rearwardly, effecting closure of the motor circuit through the linkage just described. The method whereby the control plate I28 is rocked by the automatic division lever 888 to cause this circuit closure has been described hereinbefore.

Means have been provided whereby the selection, set in the accumulator actuator by the depression of keys on the keyboard, is locked in the actuator drum while it is out of full cycle position. A set of locking. pawls 848 (Figure '7) fixed on shaft 8 are operable through arm 842 by a cam 843 fixed on the actuator shaft, so that when the actuator has rotated through a predetermined angle in either direction, the head of arm 842 is forced out of the depression 843A, in which it is normally disposed, to ride the higher periphery of the cam 843, thereby rocking the pawls 848 to enter the selected depressions in the periphery of the actuator differential mechanism. It will be observed that, during a plurality of rotations of the actuator in division operations, it is necessary that the selection be continuously locked instead of the intermittent locking effected by the cam 843. This desirable continuous locking operation is accomplished through a lever 848A connected with a gate 845 by a link 844 fulcrumed on each. The lower end of this gate 845 lies directly behind a roller 848 journaled on a stud in the lever 8l2, so that a rearward motion of the lever 8 I 2, caused by the operation of the automatic division lever heretofore described, will also rock the lock pawl 848 into locking position through the linkage just explained, holding it there until the division operation has been completed and the mechanism therefor released.

Optional control of the overdraft mechanism Means are provided whereby the overdraft control mechanism may be tripped selectively from any one of a plurality of transfer levers. A shaft 815 (Figure 12) which is journaled in and transversely slidable in a sleeve 818 securely fixed in the machine side frame is provided at its outer end with a knob 811 to facilitate transverse adjustment thereof to a plurality of positions in which it is resiliently held by a spring pressed ball 819 which is forced into any one of a series of positioning depressions in the shaft 815. On its opposite end, the shaft 815 carries a lever 818 (Figure 13) designed to cooperate with a lever 425 when transversely adjusted in alinement therewith. The distance between the said depressions in the shaft 815 is such that upon engagement of the ball 818 in successive depressions the lever 818 is positioned alternately in operative and inoperative relation with the respective transfer levers 425. The arrangement is such that a movement of the selected lever 425 caused by an overdraft will rock the lever 818 and shaft 815 toward the rear, imparting a counter-clockwise oscillation to the lever 838 which is splined on the shaft 815 by means of an integral key cooperating with a long keyway 815A.

It is obvious, therefore, that when the lever 818 is adjusted in alinement with one of the transfer levers 425, the overdraft control mechanism may be tripped from the selected transfer lever rather than from the one then associated with the lever 838. If the lever 818 is adjusted to one of its neutral positions, the overdraft control is effected from the transfer lever then associated with the wing of the lever 838 in the usual manner.

The provision of a selective overdraft control from any transfer lever renders the machine capable of performing problems in simultaneous multiplication and division, involving factors of a greater number of digits than has heretofore been possible in machines of the same ordinal capacity. In prior machines the process of double complemental division has been employed to solve problems of the type (a+b) Xc by registering the complement of the dividend in the left hand numeral wheels of the accumulating mechanism, the divisor and multipllcand are then set in the left and right hand orders of the keyboard, respectively, and the machine is run additively until the overdraft is corrected. The carriage is then shifted one place to the left and the automatic division mechanism is used to complete the operation, at the end of which the result is registered in the right hand numeral wheels of the accumulating mechanism.

The above outlined method has the disadvantage that as the accumulator carriage is shifted to the left the numeral wheels in which the highest order digits of the result have been registered are positioned in alinement with the orders of the actuator in which the lowest order digits of the divisor are set. Consequently an undesired subtraction will occur unless the operation is stopped prior to such shift. In any event, the number of digits of the various factors of the problem is limited by the condition outlined above and as a result such method has not been widely used.

The provision of an optionally operable selective control for the overdraft mechanism overcomes the difliculty outlined above and greatly increases the number of digits which may be contained in the various factors. The operation of such mechanism can. be more readily understood in connection with the solution of a problem and, for the purposes of illustration. the following problem has been selected: (1366+1832) X1173. It has been assumed that the accumulator mechanism contains eighteen numeral wheels and that the keyboard and the actuator contain nine orders each.

The dividend is set in the four right hand columns of the keyboard and its complement is entered in the accumulator with the same in its extreme right hand position. The divisor, 1832, is then set in the four right hand columns of the keyboard, and the multiplicand, 1173, is set in the four left hand columns thereof. These two numoperation of bar 288 until the positive overdraft has removed the nine standing in the numeral wheel aligned with lever 516 as a result of entering the complement therein. These Opera-- tuating mechanism and said controlmechanism,

' accumulator tions leave the following registration in the No valuehaving been set in the middle or fifth column of the keyboard the numeral wheel aligned therewith at any time will overdraft upon an oversubtraction and the movement of the fifth order transfer lever is used to trip the overdraft control mechanism, the lever 616 being adjusted in alinement therewith. The accumulator carriage is then shifted one place to the left and the operation of automatic division is used to complete the solution of the problem. A short tabular summary of the problem is given below wit certain of the intermediate ordinal divisions om tted,

The result, 874.6277 is obtained .correct to four decimal places, that is, with seven correct figures instead of the two correct places which can-be obtained when the overdraft control is tripped from the highest. order transfer lever.

The above outlined method can also be ,utilized to automatically obtain the product of two numbers of large denomination by considering the problem as a division of one of such numbers by the number 1 and a multiplication'of the quotient obtained therefrom by'the other number. While other advantageous results can be obtained by providing a selective control for the overdraft mechanism, those outlined above illustrate sufficiently the operation and use of such a mechanism and the advantages to be obtained therefrom.

I claim:

1. In a motor driven calculating machine, numeral wheels, actuating mechanism therefor, overdraft control mechanism associated therewith adapted to initiate successive reversals of said actuating mechanism, means for enabling said 'ac-' normally inoperative means for disabling said enabling means, and manually operable control means adapted to enable said enabling means upon movement in one direction, and to enable said disabling means upon movement in the opposite direction.

2. In a motor driven calculating machine, numeral wheels, actuating mechanism v therefor, overdraft control mechanism associated therewith, a spring retracted member movable to operative position to initiate a calculating operation, normally inoperative means operable by said actuating means upon an overdraft registration to terminate the operation, and means operable by said movable member on return thereof to inoperative position to enable said normally inoperative means.

3. Ina motor driven calculating machine, nu-

meral wheels, actuating mechanism therefor,- overdraft control mechanism associated therewith adapted to initiate successive reversals of said actuating mechanism, a spring retracted control member movable to two positions, means controlled by said member upon movement to operative position for enabling said control mechanism,

, a latch for said last named means, and independently operated means conditioned by said member upon movement by said spring to inoperative position for disabling said latch.

4. In a calculating machine, displaceable numeral wheels, mechanism operable by an over-' draft registration of a selected numeral wheel, and means for selectively positioning said mechanism in operative relation with a selected numeral wheel in any of a plurality of displaced positions thereof.

5. In a calculating machine, a shiftable car- I riage, numeral wheels thereon, an actuator therefor comprising a plurality of actuating members, an overdraft mechanism operable by an overdraft registration of said numeral wheels, and means operable by any of a plurality of said numeral wheels for selectively controlling said overdraft mechanism from a point contiguous to any of said actuating members, and means for retaining said selective control mechanism in oper ative or inoperative position.

'7. In a calculating machine, a shiftable carriage, numeral wheels thereon, actuating mechanism therefor comprising a plurality of numeral wlieel actuating devices, control devices operable by said numeral wheels for controlling said mechanism, and means operable by any of a plurality of said numeral wheels for selectively controlling said mechanism from a point contiguous to any one of a plurality of'said actuating devices.

' HAROLD T. AVERY. 

